SOLID原則のSとDとテストの話 - 「Swiftらしく設計する」Another / 20181221 #roppongiswift

ROPPONGI.swift 第6回 望年会 - connpass
https://visits.connpass.com/event/111355/
での発表資料です。

一般発売目前となった「iOSアプリ設計パターン入門」
https://peaks.cc/iOS_architecture
の第3章「Swiftらしく設計する」
で説明したSOLID原則のS(単一責任原則)とD(依存関係逆転の原則)について、
ちょっと角度を変えてテストの側面から捉えてみます。

Transcript

1. SOLIDݪଇͷSͱDͱςετͷ࿩
   ʮSwiftΒ͘͠ઃܭ͢ΔʯAnother
   by.
   2018/12/21 Roppongi.swift
   1
   

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2. takasek
   @takasek
   Works
   OSS: ActionClosurable౳
   App: PasteTheType
   Articles
   ʮίϯύΠϧΤϥʔ΍ϥϯλΠϜΤϥʔΛ௚͍ͯ͘͠
   ͚ͩͰiOSΞϓϦͷ࡞Γํ͕Θ͔ΔϓϩδΣΫτʯ
   ʮ͓લΒ͕ModelͱݺͿΞϨΛͳΜͱݺͿ΂͖͔ʯ
   ʮiOSΞϓϦઃܭύλʔϯೖ໳ʯʢڞஶʣ
   2
   

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3. ʮiOSΞϓϦઃܭύλʔϯೖ໳ʯ
   ઌߦൃച഑ૹதʂ
   Ұൠൃചؒۙʂ
   takasek୲౰ষ
   ୈ1ষʮઃܭ͢Δͱ͍͏͜ͱʯ
   ୈ2ষʮઃܭʹύλʔϯΛద༻͢Δલʹʯ
   ୈ3ষʮSwiftΒ͘͠ઃܭ͢Δʯ
   ୈ4ষʮΞʔΩςΫνϟͷύλʔϯΛௗᛌ͢
   Δʯ
   3
   

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4. App Client
   Melting Pod #1
   1/10ʹ΍Γ·͢
   4
   

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5. ୈ3ষʮSwiftΒ͘͠ઃܭ͢Δʯ
   SOLIDݪଇ΍ɺProtocol Oriented Programming,
   Swiftͷݴޠػೳʢenum, generics, etcʣΛ࢖ͬͯ
   ίʔυΛʮΑ͍ઃܭʯ΁ͱվળ͍ͯ͘͠ষ
   5
   

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6. Α͍ઃܭ #ͱ͸
   6
   

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7. ୈ2ষʮઃܭʹύλʔϯΛద༻͢Δલʹʯ
   ཁ໿
   • ໊લʹΑͬͯ੹຿ͷڥքΛ໌ࣔ͢Δ
   • ෆద੾ͳ੹຿ʢίʔυͷष͍ʣ͸ɺ
   ɹઃܭͷݪଇʹΑͬͯݴޠԽͰ͖Δ
   • ඞཁʹԠͯ͡ઃܭͷݪଇɺύλʔϯΛద༻͢Δ͕ɺ΍Γ͗͢͸ې෺
   • ઃܭ͸୯७ʹ࢝ΊɺϦϑΝΫλϦϯάΛਐΊͳ͕Β
   ɹΠςϨʔςΟϒʹਐԽͤ͞Δ
   • ϦϑΝΫλϦϯάͷͨΊʹ͸ɺςετ͠΍͍͢ઃܭ͕લఏ
   7
   

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8. 3ষͷվળର৅ίʔυʢൈਮʣ
   final class MessageSender {
   private let api = CommonMessageAPI()
   init(messageType: MessageType) { ... }
   private var isTextValid: Bool { ... }
   private var isImageValid: Bool { ... }
   var isValid: Bool {
   switch messageType {
   case .text: return isTextValid
   case .image: return isTextValid && isImageValid
   case .official: return false // OfficialMessage͸͋Γ͑ͳ͍
   }
   }
   ...
   8
   

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9. MessageSender ͷ
   ໰୊఺
   όϦσʔγϣϯϩδοΫ͕
   MessageSender ͷதͰ
   ๲ΒΈ͍͗ͯ͢Δ
   9
   

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10. όϦσʔγϣϯϩδοΫ
    ͕๲ΒΈ͍͗ͯ͢Δͱ
    Կ͕ਏ͍͔
    10
    

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11. MessageSender ͷ
    ςετΛ
    ߟ͑ͯΈ·͠ΐ͏
    11
    

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12. let sut = MessageSender(messageType: .image)
    let cases: [(line: UInt, text: String?, image: UIImage?, expects: Bool)] = [
    (line: #line, text: nil, image: UIImage(), expects: true),
    // text͕͋Δ৔߹ɺ80จࣈҎ಺Ͱͳ͍ͱinvalid
    (line: #line, text: String(repeating: "x", count: 80), image: UIImage(), expects: true),
    (line: #line, text: String(repeating: "x", count: 81), image: UIImage(), expects: false),
    // image͕ͳ͚Ε͹͍͔ͳΔ৔߹΋invalid
    (line: #line, text: nil, image: UIImage(), expects: false),
    (line: #line, text: String(repeating: "x", count: 80), image: UIImage(), expects: false),
    (line: #line, text: String(repeating: "x", count: 81), image: UIImage(), expects: false),
    ]
    cases.forEach {
    sut.text = $0.text
    sut.image = $0.image
    XCTAssertEqual(sut.isValid, $0.expects, line: $0.line)
    }
    12
    

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13. ໰୊ͳ͍
    13
    

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14. ຊ౰ʹʁ
    14
    

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15. MessageSender ͷ
    ผͷ໰୊఺
    API͕۩ମతͳ௨৴ϩδοΫͱ
    ີ݁߹͍ͯ͠Δ
    15
    

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16. ղܾࡦɿ ґଘؔ܎ٯసͷݪଇ
    ❌
    final class MessageSender {
    private let api = CommonMessageAPI()
    init(messageType: MessageType) {
    ...
    }
    }
    16
    

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17. ղܾࡦɿ ґଘؔ܎ٯసͷݪଇ
    ⭕
    final class MessageSender {
    private let api: CommonMessageAPIProtocol // protocolԽ
    init(messageType: MessageType,
    api: CommonMessageAPIProtocol) { // DI
    ...
    }
    }
    17
    

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18. Swift Complier Error
    18
    

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19. let sut = MessageSender(
    api: /*
    !
    ͜͜ʹԿΛೖΕΑ͏…ʁ */,
    messageType: .image
    )
    let cases = [
    ...
    ]
    cases.forEach {
    sut.text = $0.text
    sut.image = $0.image
    XCTAssertEqual(sut.isValid, $0.expects, line: $0.line)
    }
    19
    

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20. όϦσʔγϣϯͷςετ
    Λ͍ͨ͠ͷʹ
    ؔ܎ͷͳ͍ґଘ͕͋Δ
    20
    

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21. ղܾࡦɿ ୯Ұ੹೚ݪଇ
    • όϦσʔγϣϯϩδοΫΛ੾Γग़͢
    • ޓ͍ʹ஌Δඞཁͷͳ͍TextMessageͱImageMessageͷ
    ValidatorΛ෼ׂ
    21
    

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22. struct ImageMessageInputValidator {
    let image: UIImage?
    let text: String?
    var isValid: Bool {
    if image == nil { return false }
    if let text = text, text.count > 80 { return false }
    return true
    }
    }
    ※ iOSઃܭຊͰ͸͞ΒʹઌͷਐԽ͕͋Γ·͢ɻ
    ɹؾʹͳΔਓ͸ຊΛಡΜͰ͔֬ΈͯΈΖʂ
    22
    

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23. վળςετίʔυ
    // apiͷ͜ͱΛҙࣝ͢Δඞཁ͕ͳ͘ͳͬͨ
    // messageType΋ཁΒͳ͘ͳͬͨ
    let cases = [
    ...
    ]
    cases.forEach {
    let sut = ImageMessageInputValidator(
    text: $0.text,
    image: $0.image
    )
    XCTAssertEqual(sut.isValid, $0.expects, line: $0.line)
    }
    23
    

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24. Happy
    24
    

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25. ܕͷ੹຿Λখ͘͞อͭͱ
    ςετ΋͠΍͍͢͠ංେԽ΋๷͛Δ
    25
    

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26. ͱ͜ΖͰ
    26
    

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27. Α͘ݟΔίʔυ
    final class HogeListPresenter {
    private func didReceiveResponse(hoges: [Hoge]) {
    updateViewDataArray(with: hoges)
    }
    private func updateViewDataArray(with hoges: [Hoge]) {
    self.viewDataArray = hoges.map {
    if hoge.isXXX {
    return HogeViewData(...)
    } else {
    return HogeViewData(...)
    }
    }
    }
    }
    27
    

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28. Α͘ݟΔίʔυ
    final class HogeListPresenter {
    private func didReceiveResponse(hoges: [Hoge]) {
    updateViewDataArray(with: hoges) // Ͳ͏͍͏෭࡞༻͕͋Δͷ͔҉໧త
    }
    private func updateViewDataArray(with hoges: [Hoge]) {
    self.viewDataArray = hoges.map {
    if hoge.isXXX {
    return HogeViewData(...)
    } else {
    return HogeViewData(...)
    }
    }
    }
    }
    28
    

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29. ͡Ό͋͜͏͢Δʁ
    final class HogeListPresenter {
    private func didReceiveResponse(hoges: [Hoge]) {
    self.viewDataArray = makeViewDataArray(from: hoges)
    }
    private func makeViewDataArray(from hoges: [Hoge]) -> [HogeViewData] {
    return hoges.map {
    if hoge.isXXX {
    return HogeViewData(...)
    } else {
    return HogeViewData(...)
    }
    }
    }
    }
    29
    

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30. [Hoge] Λ [HogeViewData] ʹ
    ม׵͢Δͷ͸ผʹ
    HogeListPresenter
    Πϯελϯε͡Όͳͯ͘΋
    Ͱ͖Δ
    30
    

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31. ͦΕͳΒ͜͏Ͱ͸
    final class HogeListPresenter {
    func didReceiveResponse(hoges: [Hoge]) {
    self.viewDataArray = hoges.map(HogeViewData.init)
    }
    }
    private extension HogeViewData {
    init(hoge: Hoge) {
    ...
    }
    }
    31
    

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32. • makeViewDataArray(from:) ͱ͍͏Α͏ͳ
    ৑௕ͳ໊લͰͳ͘ͳͬͨ
    • HogeListPresenter ʹର͢Δ෭࡞༻͕ͳ͍͜ͱ͕໌֬
    • HogeViewData ୯ମͰςετ΋Ͱ͖Δߏ଄ʹͳͬͨ
    32
    

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33. ੹຿Λਖ਼͘͠อͭ͜ͱͰ
    ߟ͑Δ͜ͱ͕ݮΓ
    ςετ͠΍͘͢ͳΓ
    API͕γϯϓϧʹͳͬͨ
    33
    

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34. Happy
    34
    

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35. Happy
    ͳઃܭ͍͖ͯ͠·͠ΐ͏
    35
    

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